Authorities in Germany have ordered free-range flocks inside. And Dutch officials have decided to house flocks after a number of dead wild birds were found in Amsterdam.

The Dutch cases have not yet been confirmed as carrying the disease, but as it is just 150 miles off the east-coast of England, the situation has caused alarm this side of the North Sea.

A spokesman for Defra urged farmers to be vigilant and added that the UK’s risk level was “low but heightened” for an incursion of avian influenza.

“The outbreak in Hungary and the wild bird cases in Poland are indicative of further evidence that this virus is circulating in wild birds and therefore incursions into poultry farms can be expected,” he warned.